Death has thrown up a great paradox of our times. On the one hand, conventional wisdom says that we have managed to shut it from our thoughts more successfully than any previous age; and on the other, never before have there been so many sites to the memory of the dead. On the one hand, it's a modern taboo; on the other, a sorrowful fact so well recognised by multiplying numbers of park benches, monuments and minutes of silence at football grounds that any black-coated Victorian, preserving hair from the heads of his dear departed children in a locket, would feel perfectly at home.

All of them are long after the fact. Some of them may be explicable as long-overdue remedies to unjust neglect, but why did the spate of building happen when it did, in the first few years of the present century? Was it because the last survivors of the first world war were dying then, reminding us to remember, and that there was money to spare in the boom years? Or that Diana, princess of Wales (down whose "memorial path" lie several of these monuments) had whetted a public appetite for loss? Perhaps new wars – Iraq, Afghanistan – played their part; perhaps it was the books of Max Hastings, Patrick Bishop and Antony Beevor. Probably it was the accumulation of all of these things, as well as something valedictory in the air that suggested a familiar version of Britain was vanishing.

Aesthetically, most of the new memorials fail to move or inspire as they should. According to the historian David Cannadine, Britain between the world wars "was probably more obsessed with death than [in] any other period of modern history", but it was also lucky, in the opinion of Gavin Stamp, to have architects who had been trained in classicism and weren't at all scared by the monumental, because what they were being asked to create were memorials to human slaughter rather than military glory. As Stamp writes in The Memorial to the Missing of the Somme, his brilliant study of Lutyens' monument at Thiepval, this was a radical idea to a European civilisation that erected triumphal arches, named railway termini after victories and hoisted stone admirals aloft on columns. In the Cenotaph, Lutyens avoided representations of heroism and victory or any religious symbolism, despite the pressure of bishops who vilified the design as "pagan". Just three words, "THE GLORIOUS DEAD", are carved on it, and though you might cavil at the adjective, thinking of how men died, the fact remains that the Cenotaph gave itself a future by evoking two readily felt eternals, death and loss.

None of the modern memorials can match it. Walking around them this week, I was struck by how they divided between banal literalism and meaningless abstraction. Bomber Command has too many pillars, and the bronze figures of the flyers are too perfectly realised in their detail. What helps humanise it in this, its first remembrance season, are the wooden crosses that visitors have stuck in the top of the statue's bronze boots and the photographs they've left behind of young men with names such as Johnny Tucker and Jack Forrest. Further on, the slanting posts of the New Zealand memorial bristle incomprehensibly. A wan inscription composed by Ben Okri – "Our future is greater than our past" – decorates the Commonwealth Memorial Gates at the top of Constitution Hill. Australia's has a low, boomerang-shaped wall of grey-green stone, rather ugly, but it displays Hyde Park Corner's one recent stroke of genius: an optical trick means that at a distance the names of famous battles – Gallipoli, Imphal, El Alamein – loom large, but closer to dissolve into the often obscure names of the 24,000 settlements – Balloong, Morans Crossing, Yallamurray – where the dead were born.

I walked north, past the unforthcoming minimalism of the 7/7 memorial, until I reached Animals in War. A procession of the species that armies have used to carry supplies or haul guns, or fly messages or kill vermin, marches across a frieze: elephants, camels, horses, bullocks, donkeys, a flight of pigeons, a dog, a cat. The inscriptions praise "all the animals that served and died alongside British and allied forces in wars and campaigns throughout time ... they all played a vital role … in the cause of human freedom". Elsewhere, in larger letters, are the words: "They had no choice." No, you think, and neither did the Royal Scots at Passchendaele. As for the cause of human freedom throughout time, does this apply to the horses of the Light Brigade? And where stand the pack mules employed by the kaiser? Never mind the cause of human freedom – what about their selfless work meeting the human appetite? Doesn't that demand a memorial the height of the Eiffel tower outside every abattoir?

The names of the benefactors are inscribed on the reverse, among them the American Kennel Club, Mr and Mrs Charlie Watts and the Mail on Sunday. Bomber Command can similarly thank Lord Ashcroft, Richard Desmond and the late Robin Gibb. The names are prominent, either on the memorials or in the publicity. The Tomb of the Unknown Sponsor is a shy, old-fashioned idea.

The 11th hour of the 11th day of the 11th month arrives tomorrow. Perhaps, after the crowd has dispersed, we'll go down to have a look at Charles Jagger's monument to the Royal Artillery, which may be the most affecting of London's memorials. Its frieze, blurred in places by corrosive pollution, shows the horror of mud and struggle as vividly as any art can. Bronze artillerymen stand on three sides. On the fourth, another lies dead under his greatcoat with a helmet on his chest. The inscription comes from Shakespeare's Henry V, spoken after Agincourt when the young king learns of the toll of princes among the French: "HERE WAS A ROYAL FELLOWSHIP OF DEATH." As humbling devices, created in a time of genuine sorrow, the monuments by Jagger and Lutyens will never be surpassed.

Architect Peter Eisenman has said he couldn’t build his Berlin Holocaust memorial today, as Europe has become too antisemitic. But the very way culture has framed the Holocaust has allowed right-wing populism to flourish